全文原句：
A 1993 study by the European Federation for Transport and Environment found that car transport is seven times as costly as rail travel in terms of the external social costs it entails — congestion, accidents, pollution, loss of cropland and natural habitats, depletion of oil resources, and so on.
Yet cars easily surpass trains or buses as a flexible and convenient mode of personal transport.
It is unrealistic to expect people to give up private cars in favour of mass transit.
🧱 第一句解析：
A 1993 study by the European Federation for Transport and Environment found that car transport is seven times as costly as rail travel in terms of the external social costs it entails — congestion, accidents, pollution, loss of cropland and natural habitats, depletion of oil resources, and so on.
结构分析：
成分 内容 作用
主语 A 1993 study by the European Federation for Transport and Environment “欧洲交通与环境联合会于1993年的一项研究”
谓语 found “发现”
宾语从句 that car transport is seven times as costly as rail travel... “发现汽车运输的成本是铁路的七倍……”
宾语从句内部结构：
car transport is seven times as costly as rail travel
= 汽车运输比铁路运输贵七倍。
👉 as … as = “和……一样（的）”，这里前面加 seven times → “是……的七倍”。
短语讲解：
in terms of = “就……而言”，相当于 with regard to / regarding
→ “就……方面来说”
the external social costs it entails
= “它带来的外部社会成本”
external（外部的）
social costs（社会成本）
entail（带来、导致）
破折号后的内容是对 social costs 的具体列举：
congestion（交通拥堵）, accidents（事故）, pollution（污染）, loss of cropland and natural habitats（耕地和自然栖息地的损失）, depletion of oil resources（石油资源的消耗）, and so on（等等）。
✅ 译文：
1993年，欧洲交通与环境联合会的一项研究发现：
从其带来的外部社会成本来看，汽车运输的花费是铁路运输的七倍——包括拥堵、事故、污染、耕地与自然栖息地的损失、石油资源的耗竭等等。
🧱 第二句：
Yet cars easily surpass trains or buses as a flexible and convenient mode of personal transport.
结构：
主语：cars
谓语：surpass（超过）
宾语：trains or buses
状语：easily（轻易地）
补语部分：as a flexible and convenient mode of personal transport（作为一种灵活方便的个人交通方式）
✅ 译文：
然而，汽车作为一种灵活、方便的个人交通方式，远远超过火车或公共汽车。
🧱 第三句：
It is unrealistic to expect people to give up private cars in favour of mass transit.
结构分析：
It = 形式主语（真正主语是后面的不定式短语）
is unrealistic = “是不现实的”
to expect people to give up... = 真正主语（期待人们放弃……）
in favour of = “转而支持 / 选择”
mass transit = “公共交通系统”
✅ 译文：
指望人们放弃私家车、转而使用公共交通，是不现实的。
🧩 全段总结逻辑：
句子 含义 逻辑作用
① 汽车的社会成本是铁路的七倍 说明汽车运输的高代价
② 但汽车更灵活、方便 对比优点
③ 要人放弃私车并不现实 得出结论，体现现实困境
👉 主题：
🚗 汽车运输的社会代价高，但因其便利性，人们难以放弃私家车